Mechanical movement.



No. 678,767. Patented July l6, ML 0. r. norm.

MECHANIC AL MOVEMENT.

(Application filed m 20, 1901.\

(I10 Mode'l.)

mHIIIIIU Eg Ill we unnms nuns co. moraumm, WASHINGTON, n

- Uwrrnn Srarns Parent Canton,

CHARLES F. ROPER, OF HOPEDALE, MASSACHUSETTS, ASSIGNOR TO DRAPERCOMPANY, OF SAME PLACE AND PORTLAND, MAINE.

MECHANICAL MOVEMENT.

SPECIEICAEIGN forming part of Letters Batent N0. 678,767, dated July 16,19011.. Application filed March 20,1901. Serial No. 52,060. (No model.)

To aZZ whom, it may concern:

Be it known that 1, CHARLES F. ROPER, a citizen of the United States,residing at Hope dale, in the county of Worcester and State ofMassachusetts, have invented an Improvement in lVlechanicalli Iovements,of which the following description, in connection with the accompanyingdrawings, is a specification, like characters on the drawingsrepresenting like parts.

It is the object of my invention to provide a novel mechanical movementwhich is especially adapted for converting rotary into an even anduniform reciprocating movement.

Where the ordinary crank and pitman is employed for converting rotaryinto reciprocating movement, or vice versa, the speedof thereciprocating element varies at different points of the stroke, and thesaid reciprocat- 2'0 ing element will dwell for a considerable length oftime at the end of its stroke or when the crank-arm is passing thedead-center point. In order to avoid this diffieulty, I have connectedthe end of the pitman or other connection to the crank-shaft by aconnecting member which is in the nature of a differential crank-arm,the said crank-arm operating to give the end of the pitman to which itis connected a variable angular velocity, the

angular velocity of the said end of the pitman having agradually-accelerated movement at the end of the stroke or as thecrankarm approaches or recedes from the deadcenter point and a retardedmovement during the intermediate portions of the stroke.

-Mechanism is also provided to cause the end of the pitman to pass thedead-center point with a greatly-accelerated movement, so that thereciprocating element is given a quick re- 0 verse at the end of itsstroke.

Preferably my differential crank-arn1 comprises two members, one ofwhich is fast upon the crankshaft and is for convenience referred to asthe fixed member and the other of which is in the nature of acompensating member and is loosely mounted upon the said crankshaft, thesaid compensating member having connected thereto the pitman or otherconnection between the crank-arm and the reciprocating element. The twomembers of the differential crank-arm are suitably geared together, andsuitable means, preferablya cam, is employed to give the compensatingmember a varying difierential movement with respect to the fixed member,the movement of the compensating member beinga gradually-acceleratedmovement with reference to the fixed member as the crankarm approachesor recedes from the deadce'nter point and a retarded movement inter- 6omediate these points, such varying differential movement of thecompensating member with reference to the fixed member operating to giveto the reciprocating element an even uniform speed throughout itsreciprocation. As the reciprocating element reaches the end of itsstroke suitable mechanism is provided for giving to the compensatingmember a quick forward movement with reference to the fixed member,whereby the compensating member and pitman or other connection arequickly thrown past the dead-center point and the compensating elementwill begin its return stroke without any appreciable delay or dwell atthe end of the stroke.

Referring to the drawings, Figures 1 and 2 are plan views of mymechanical movement, showing different positions thereof. Fig. 3 is asection on the line a: 33, Fig. 1; and Figs. 4,

5, 6, and 7 are detail views of the two mem- 8o bers of the differentialcrank-arm.

The crank-shaft or other driving-shaft is designated by 3, and this ismounted in any suitable bearings 4E and may be driven in any suitableway, according to the use to which the device is to be put. Asillustrated in the drawings, the said crank-shaft is given a uniformrotary movement by means of a gear 5, fast thereon, which meshes withand is driven by another gear 6 upon a suitable driving- 0 shaft. Therotary movement of the crankshaft or driving-shaft 3 is converted into areciprocating motion and is communicated to the reciprocating element(not shown) by means of the crank-arm C and the pitman- 5 rod or otherconnecting member P. The crank-arm C is designed, as stated above, togive to the reciprocating element a gradual acceleration as itapproaches and leaves each end of its stroke and a retarded motionduring the central portion of the stroke, thus counteracting orbalancing the uneven reciprocating motion due to the ordinary crankarmand giving to the reciprocating element a resultant reciprocation whichis uniform throughout the entire length of the stroke. To accomplishthis result the crank-arm O is what I term a differential crank-arm, itcomprising two members, one of which,10, is rigidly fastened to thecrank-shaft 3 by any suitable means, preferably by the usual key,and isforconvenience termed thefixed member, While the other member 11, whichis called the compensating memberandwhich is pivotally connected to thepitman P, is supported in some suitable way for turning movementrelative to the fixed member, it being shown in this embodiment of myinvention as loosely mounted upon the crank-shaft. The fixed member andthe compensating member of the crank-arm are suitably geared together,and a suitable mechanism is provided for giving the compensating membera varying differential motion with respect to the fixed or fast member,as above described. The free end of the fixed or fast member 10 haspivotally mounted thereon the segmental gear 15, the said gear 15 beingprovided with the arm 16, between which arm and the gear 15 the bearing17 in the end of the arm or fixed member 10 is positioned, a pivot-pin18 passing through suitable apertures in the gear 15 and arm 16 and thebearing 17 serving to thus pivotally connect the segmental gear with thefast member 10.

The compensating member 11 of the crankarm, which is mounted for turningmovement relative to the fixed member 10, may be supported in anysuitable way, one good and convenient way being to loosely mount thesame upon the crank-shaft, as stated, and the said compensating memberhas rigidly secured thereto, as by screws 19, the segmental gear 20,which meshes with the segmental gear 15, as plainly seen in Figs. 1 and2. The compensating member 11 has adjustably pivoted thereto the pitmanP, preferably by m aking the said compensating member with the slot 21,in which the bolt 22, passing through the end of the pitman, isadjustably secured. With this construction it will be obvious that ifthe segmental gear 15 is turned about its pivot the compensating member11 will. be given a differential movement with respect to the fixedmember 10 of the crank-arm, and by providing suitable mechanism forgiving to the compensating member 11 a graduallyaccelerated movementwith reference to the fixed member 10 as the crank-arm approaches orrecedes from its dead-center pointand a gradually-retarded movementduring the central portion of the stroke of the crank-arm thereciprocating element will be given a resultant movement which will beuniform throughout all points of its stroke, and by giving to the gear15 a quick turn just as the dead-center point is reached thecompensating member and pitman P will be quickly thrown past thedead-center point, so that the stars"? reciprocating element will notdwell at the end of its stroke. In order to thus control the segmentalgear 15, so as to give to the compensating member 11 a varyingdifferential movement with respect to the fixed mem-- ber 10, Ipreferably provide the said segmen tal gear with an arm 23, which bearsagainst the interior cam-surface of a suitable cam 25, the said cambeing supported in any suitable way and surrounding the differentialarm, as shown in Figs. 1 and 2.-

In order to reduce friction between the arm 23 and the cam-surface, Ipreferably pivot to the arm 23 and antifriction-roll 26, which bearsagainst the cam-surface, and for this purpose the arm 23 will be madeforked, as illustrated in Fig. 6, between the branches of which theantifriction-roll may be pivoted.

The cam 25 is whatIterm a double cam, it having two duplicatecam-surfaces, against one of which the roll 26 operates during theforward movement of the reciprocating element and against the other ofwhich the said roll operates during the return movement of the saidreciprocating element. Each portion of the cam has the point or rise 30so positioned that the roll 26 will engage the same just as thecrank-arm is passing its deadcenter point, the flattened portion 31,which the roll 26 engages as the reciprocating element begins itsreciprocation, the graduallyreceding eccentric portion 32, which theroll 26 engages during the central portion of the stroke, and thegradually-rising portion 33, which the roll engages as the reciprocatingelement approaches the end of its stroke.

The operation of the cam and the compensating crank-arm will be readilyunderstood from the foregoing description and is as follows: Assumingthat the crank-arm is moving in the direction of the arrow, Fig. 1, andthat the crank-arm is on a deadcenter at the right hand in Figs. 1 and2, in which case the roll 26 will be just about to pass the crown of therise or point 30, it will be seen that as the fast member 10 of thecrank-arm moves through the first portion of its stroke the roll 26 inpassing over the flattened portion 31 of the cam-surface operates toturn the gear 15 backward and thus through the gear 20 give to thecompensating member 11 a forward differential movement with respect tothe fixed member 10. As the differential crank-arm 0 moves into theposition shown in Fig. 1 the gradually-receding portion 32 of thecam-surface, which portion has a progressively-increased radius, allowsthe gear 15 to gradually swing clockwise or forward upon its pivot 18,such forward movement of the gear 15 on its pivot serving to give to thecompensating member 11 of the crank arm a backward differential movementwith respect to the fixed member 10, the said compensating member 11falling behind the fixed member 10, so that the reif the pitman wereconnected directly to the fixed arm, for in the position shown in Fig. 1an ordinary crank-arm is in its most effective position. When thecrank-arm reaches the position shown in Fig. 2, the roll 26 engages therising portion 33 of the cam-surface and operates through the segmentalgears to give to the compensating member 11 a forward differentialmovement with respect to the fixed member 10, such increase of speed ofthe compensating member over the fixed member being sufficient tocounteract the normally-retarded movement of the reciprocating elementas it approaches the end of the stroke due to the ordinary crank motion,and thus give to the said reciprocating element a movement which is ofthe same speed as its movement during the center portion of the stroke.As the roll 26 passes over the rise 30 the segmental gear 15 is given aquick forward turn, which, as will be readily understood, operates tothrow the compensating member and pitman P past the deadcenter pointwith a greatly-accelerated movement, so that the reciprocating elementwill upon its reaching the end of its stroke immediately begin itsreturn movement without any appreciable dwell.

Where it is desired to convert a uniform rotary motion into an even oruniform reciprocating movement, as above described, it will beunderstood that in the practical construction of the cam 25 said camwill be so designed and the various portions of the camsurface will beso shaped as to give to the compensating member of the crank-arm arotary motion of such a character that the motion of the reciprocatingelement Will be uniform.

It will thus be seen that I have provided a very simple and efficientcrank motion and at the same time provided means whereby thereciprocating element is given a quick reverse at the end of its strokeand is not allowed to dwell or pause, as is the case when an ordinarycrank-motion is employed.

It will be obvious to those skilled in the art that my invention may beemployed in any device where it is desired to convert rotary motion intoan even reciprocating movement, and it will also be obvious that byvarying the contour of the cam-surface the speed of the reciprocatingelement may be varied at different portions of its stroke, so that by myinvention it is possible to convert a rotary motion into a reciprocatingmotion of uniform speed or of varying speed, as may be desired.

Having described my invention, What I claim, and desire to secure byLetters Patent, 1s

1. In a mechanical movement-,a crank-shaft, a pitman, a differentialcrank-arm connecting said crank-shaft and pitman, said crank-armcomprising two members, and gears connecting the same, and means to giveone of said members a variable differential movement said compensatingmember with relation to the other during the rotation of thecrank-shaft.

2. In a mechanical movement, a crank-shaft, a pitman, a differentialcrank-arm comprising two members, said crank-arm connecting thecrank-shaft and pitman, and means to give one of said members of thecrank-arm a variable differential movement with respect to the otherduring the rotation of the crank-shaft.

3. Means for converting rotary into reciprocating movement, said meanscomprising a rotating element, a differential crank-arm comprising twomembers connected to and having the same axis of rotation as saidrotating element, means to give one of said members an accelerateddifferential movement with respect to the other member when thecrank-arm is approaching or receding from its dead-center point, andmeans to connect the crank-arm with the reciprocating element.

at. Means for converting rotary into recip rocating movement, said meanscomprising a rotating element, a differential crank-arm connected to therotating element, said crankarm comprising two members rotating about acommon axis, means to give one of said members an accelerateddifferential movement with respect to the other when the crankarm isapproaching or receding from its deadcenter point, and a retardeddifferential movement during the remainder of the stroke, andconnections between the crank-arm and the reciprocating element.

5. A mechanical movement comprising a shaft, a crank-arm connectedthereto, said crankarm comprising a member fast on the shaft, and amember loose thereon, gears connecting said members,and means to givesaid loose member a differential movement with respect to the fastmember.

0. A mechanical movement comprising a shaft, a crank-arm connectedthereto, said crank-arm comprising a member fast on the shaft, and acompensating member loose thereon, gear connections between saidmembers,means to give said compensating member a varying differentialmovement with respect to the fast member, and connections between andthe reciprocating element.

7. A crank-motion for giving a uniform speed of reciprocation,comprising a shaft, a

differential crank-arm thereon, said crankarm comprising a member faston said shaft, a compensating member loose thereon, means for connectingsaid members for relative movement, and means for giving to thecompensating member a forward differential movement as the crank-armapproaches or recedes from the end of its stroke, and a backwarddifferential movement during the central portion of its stroke.

8. Means for converting rotary motion into reciprocating motion, saidmeans comprising a shaft, a differen tial crank-arm thereon, saidcrank-arm comprising a member fixed to the shaft, a compensating memberloose upon IIO the shaft, a gear pivotally mounted upon the fixed memberand engaging the compensating member, said gear having an arm, and a camsurrounding the crank-arm and cooperating with the arm on the gear,whereby the compensating member is given a varying differential motionwith respect to the fixed member.

9. Means for converting rotary into reciprocating motion, comprising ashaft, a differential crank-arm thereon, said crank-arm comprising amember fixed to the shaft, and a compensating member loose thereon, agear pivotally mounted upon the fixed member, a cooperating gear on theloose member, said pivotally-mounted gear having an arm, and a camsurrounding the crank-arm and cooperating with the arm on the gear, saidcam being so shaped as to give to the compensating member a forwarddifferential movement with respect to the fixed member as the crankarmapproaches or recedes from the end of its stroke, and backwarddifferential movement during the intermediate portion of its stroke.

10. A mechanical movement comprising a rotating element, a differentialcrank-arm connected thereto and comprising two members, and a camcontrolling the movements of one of said members relative to the other,whereby one of said members is given a differential movement withreference to the other.

11. In a mechanical movement, a rotating element, a differentialcrank-arm connected thereto, said crank-arm comprising two membersmounted for relative movement, gears connecting said members, and meansfor giving one of said members a differential movement with respect tothe other.

12. Means for converting rotary into reciprocating motion, said meanscomprising a rotating element, a differential crank-arm connectedthereto, said crank-arm comprising two me1nbers,gears connecting saidmembers, and means for operating said gears to give one of said membersof the crank-arm a varying differential movement with respect to theother, and connections between said firstnamed member and thereciprocating element.

Intestimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

CHARLES F. ROPER.

\Vitn-esses:

GEORGE OTIS DRAPER, ERNEST W. W001).

